openrvdas.logger.writers.serial_writer

 1#!/usr/bin/env python3
 2
 3import logging
 4
 5from typing import Union
 6
 7# Don't freak out if pyserial isn't installed - unless they actually
 8# try to instantiate a SerialWriter
 9try:
10    import serial
11    SERIAL_MODULE_FOUND = True
12except ModuleNotFoundError:
13    SERIAL_MODULE_FOUND = False
14
15from logger.writers.writer import Writer  # noqa: E402
16
17
18################################################################################
19class SerialWriter(Writer):
20    """
21    Writes records to a serial port.
22    """
23    def __init__(self,  port, baudrate=9600, bytesize=8, parity='N',
24                 stopbits=1, timeout=None, xonxoff=False, rtscts=False,
25                 write_timeout=None, dsrdtr=False, inter_byte_timeout=None,
26                 exclusive=None, eol='\n', **kwargs):
27        """
28        By default, the SerialWriter write records to the specified serial port encoded by UTF-8
29        and will ignore non unicode characters it encounters. These defaults may be changed by
30        specifying.
31
32        eol - if specified, append to end of records to signify end of line,
33                otherwise use \n
34
35        encoding - 'utf-8' by default. If empty or None, will throw type error.
36                Other possible encodings are listed in online documentation here:
37                https://docs.python.org/3/library/codecs.html#standard-encodings
38
39        encoding_errors - 'ignore' by default. Other error strategies are 'strict',
40                'replace', and 'backslashreplace', described here:
41                https://docs.python.org/3/howto/unicode.html#encodings
42        quiet - allows for the logger to silence warnings if not all the bits were succesfully
43                written to the serial port.
44        """
45        super().__init__(**kwargs)  # processes 'quiet', encodings and type hints
46
47
48        if not SERIAL_MODULE_FOUND:
49            raise RuntimeError('Serial port functionality not available. Please '
50                               'install Python module pyserial.')
51        try:
52            self.serial = serial.Serial(port=port, baudrate=baudrate,
53                                        bytesize=bytesize, parity=parity,
54                                        stopbits=stopbits, timeout=timeout,
55                                        xonxoff=xonxoff, rtscts=rtscts,
56                                        write_timeout=write_timeout, dsrdtr=dsrdtr,
57                                        inter_byte_timeout=inter_byte_timeout,
58                                        exclusive=exclusive)
59        except serial.SerialException as e:
60            raise serial.SerialException(f'Failed to open serial port {port}: {e}')
61
62        # 'eol' comes in as a (probably escaped) string. We need to
63        # unescape it, which means converting to bytes and back.
64        if eol:
65            if self.encoding:
66                # NOTE: Technically, it's safe to call _unescape_str() with no
67                #       encoding, it just returns the str/bytes/thing
68                #       unmodified.  But why tempt fate, right?
69                eol = self._unescape_str(eol)
70            else:
71                # if encoding has been set to '' or None, we're dealing with raw/binary
72                # output.  encode eol so we can append it safely in write()
73                eol = eol.encode()
74        self.eol = eol
75
76    ############################
77    def write(self, record: Union[str, bytes]):
78
79        # See if it's something we can process, and if not, try digesting
80        if not self.can_process_record(record):  # inherited from BaseModule()
81            self.digest_record(record)  # inherited from BaseModule()
82            return
83
84        try:
85            if self.eol:
86                record += self.eol
87            written = self.serial.write(self._encode_str(record))
88            if not written and not self.quiet:
89                logging.error("Not all bits written")
90        except KeyboardInterrupt as e:
91            raise e
92        except TypeError as e:
93            raise e
94        except serial.serialutil.SerialException as e:
95            logging.error(str(e))